JP6606917B2 - Boiler system - Google Patents

Description

  The present invention relates to a boiler system including a boiler group composed of a plurality of boilers.

  Conventionally, there has been proposed a boiler system including a boiler group having a plurality of stage value control boilers capable of burning at a plurality of staged combustion positions, and a control unit that controls the combustion state of the boiler group according to a required load. ing. Here, the stage value control boiler refers to an N position control boiler that burns at a plurality of stages of combustion positions by selectively turning on / off combustion or adjusting the size of the flame. In such a step value control boiler, the combustion rate is changed stepwise. The N position control represents that the combustion amount of the step value control boiler can be controlled step by step to the N position including the combustion stop position.

  As described in Patent Document 1, in the combustion control of a boiler system including a boiler group having a plurality of stage value control boilers, a header pressure value that is a steam pressure value inside the steam header is set in advance. It is known that the combustion state of the boiler group is controlled so that the maximum set pressure value is an upper limit value and is within the range of a pressure control band defined by a preset control width. That is, when the pressure value calculated by subtracting the control width from the maximum set pressure value is set as the lower limit value, the header pressure value is within the range of the pressure control band defined by the upper limit value and the lower limit value. The combustion state of the boiler group is controlled.

In such combustion control, the pressure control zone is divided into a plurality of pressure zones. The boiler system sets a combustion state (combustion position) corresponding to each pressure zone, and determines the combustion state (combustion position) depending on which pressure zone the header pressure value corresponds to.
For example, in the uppermost pressure band (when the required load is small) among the plurality of pressure bands, the combustion state (combustion position) in which all the boilers are located at the combustion stop position (-) corresponds to the highest pressure band. In the lower pressure band (when the required load is large), the combustion state (combustion position) in which all the boilers are located at the high combustion position (H) corresponds.

In such combustion control, a control pressure band for determining an increase in the combustion amount when the pressure decreases and a control pressure band for determining a decrease in the combustion amount when the pressure increases are defined separately, and both are shifted by a differential amount. ing.
That is, when the header pressure value is in the increasing direction (load amount decreasing direction), the header pressure value that serves as a reference for shifting from the combustion state (combustion position) X with a large combustion amount to the combustion state (combustion position) Y with a small combustion amount When the header pressure value is in the descending direction (the load amount is increasing), the header pressure value becomes a reference for shifting from the combustion state (combustion position) Y with a small combustion amount to the combustion state (combustion position) X with a large combustion amount. Is provided with a predetermined difference (differential) so that the former (when rising) is larger than the latter (when descending).
If no differential is provided, the combustion state (combustion position) may change frequently when the header pressure value fluctuates around the combustion amount increase / decrease line. In order to avoid such a change, a differential is usually provided.

JP 2011-208817 A

However, when the pressure control band is relatively narrow, the header pressure value tends to be stable when the steam load is high, but when the steam load is low, the combustion amount may be increased or decreased more than necessary for a slight pressure change. Therefore, the probability that the hunting phenomenon occurs may increase.
Specifically, at the time of low load, when the header pressure value drops from standby for all units, a combustion instruction is issued to the boilers more than necessary, and then some of the boilers start to burn and the header pressure value Even after starting to rise, the amount of combustion increases too much, so the header pressure value overshoots, eventually exceeding the set pressure, and all units may stand by.

In order to suppress such hunting, there are a method for suppressing the amount of combustion when the pressure is reduced and a method for reducing the amount of combustion early when the pressure is increased.
In the case of the method of suppressing the combustion amount at the time of the pressure drop, it is assumed that it is not possible to cope with a sudden increase in the steam load during the suppression of the combustion amount. On the other hand, in the method of reducing the combustion amount early when the pressure rises, if the steam load increases rapidly, there is a problem that the boiler is started wastefully, but the method of suppressing the combustion amount when the pressure drops It is assumed that it is safer.

  In a boiler system having a boiler group consisting of a plurality of boilers, the present invention burns early when it detects that the header pressure value has fallen to satisfy a predetermined condition, and then the header pressure value has changed from falling to rising. It aims at providing the boiler system which can prevent generation | occurrence | production of hunting by reducing quantity.

  The present invention includes a boiler group composed of a plurality of stage value control boilers capable of burning at staged combustion positions, a steam header that collects steam generated in the boiler group, and a steam pressure value inside the steam header. The steam pressure measuring means for measuring the header pressure value and the preset maximum set pressure value as the upper limit value, the set pressure range is defined by a preset control width, and is measured by the steam pressure measuring means And a control device that controls a combustion state of the boiler group so that the header pressure value falls within the set pressure range, wherein the control device is configured to increase the header pressure value. A first control pressure band storage unit for storing a first control pressure band divided into a plurality of pressure bands for determining the timing of the combustion amount decrease of the group; A first control unit that controls the timing of the combustion amount reduction of the boiler group at the time based on the first control pressure band, and shifts each pressure band of the first control pressure band downward so that the header pressure value A second control pressure zone storage section for storing a second control pressure zone, wherein the combustion group decrease timing of the boiler group at the time of the rise is lowered by a predetermined pressure from each pressure zone of the first control pressure zone; and the header pressure A second control unit that controls the timing of combustion amount reduction of the boiler group when the value rises based on the second control pressure band, and a drop that satisfies a predetermined condition occurs in the header pressure value, and then the header pressure A first detection unit that detects a first state in which the value has shifted from a decrease to an increase; and when the first state is detected by the first detection unit, the combustion amount of the boiler group when the header pressure value increases Decrease timing It switches the control to control by the second control unit, and a control switching unit, to a boiler system comprising a.

  The upper limit value of the second control pressure band is preferably equal to the upper limit value of the first control pressure band.

  The predetermined condition preferably includes the header pressure value decreasing due to the header pressure value overshooting, or the header pressure value decreasing and undershooting.

  In addition, the predetermined condition is that the header pressure value exceeds a control upper limit pressure value that is equal to or higher than an upper limit pressure value of the set pressure range, or the header pressure value is equal to or lower than a lower limit pressure value of the set pressure range. It is preferable to include that the value falls below the control lower limit pressure value that is the value of.

  Moreover, it is preferable that the said predetermined conditions include making all these boilers stand by when the said header pressure value exceeds the said control upper limit pressure value.

The control device further calculates a required steam amount MV _n for each control cycle based on a pressure deviation that is a difference between the header pressure value and the upper limit pressure value of the set pressure range. The predetermined condition is a state in which the total value of the maximum output steam amounts of all the boilers supplying steam is lower than the current required steam amount MV _n calculated by the required steam amount calculating unit, It is preferable that the header pressure value includes falling below a preset first pressure value.

  Further, the control device further shifts each pressure band of the second control pressure band downward, and sets the timing of the combustion amount decrease of the boiler group when the header pressure value increases to each of the second control pressure bands. A third control pressure zone storage section for storing a third control pressure zone, which is lower than the pressure zone by a predetermined pressure, and a timing for reducing the combustion amount of the boiler group when the header pressure value is increased. When the first state is detected by the third control unit that controls based on the first detection unit, and the first pressure detection unit further detects a gradient value with respect to the descending time of the header pressure value from a predetermined gradient value. Or a second detection unit that detects a second state in which the decrease value of the header pressure value is smaller than a predetermined decrease value set in advance, and the control switching unit includes: Front by second detector If the second state is detected, it is preferable to switch the control of the timing of the reduction combustion amount of the boiler groups at elevated the header pressure value to the control according to the third control unit.

  Further, the control switching unit further controls the timing of the combustion amount decrease of the boiler group when the header pressure value is increased by the second control unit or the third control unit by the control switching unit. After the switching, when the header pressure value does not reach the upper limit pressure value of the set pressure range and starts to decrease, the timing of the combustion amount decrease of the boiler group when the header pressure value increases is controlled. It is preferable to switch to the control by the first control unit.

  The present invention includes a boiler group composed of a plurality of stage value control boilers capable of burning at staged combustion positions, a steam header that collects steam generated in the boiler group, and a steam pressure value inside the steam header. The steam pressure measuring means for measuring the header pressure value and the preset maximum set pressure value as the upper limit value, the set pressure range is defined by a preset control width, and is measured by the steam pressure measuring means And a control device that controls a combustion state of the boiler group so that the header pressure value falls within the set pressure range, wherein the control device is configured so that the boiler pressure value increases when the header pressure value increases. A first control pressure band storage unit for storing a first control pressure band divided into a plurality of pressure bands for determining the timing of the combustion amount decrease of the group; and the header pressure A first control unit for controlling the combustion amount decrease timing of the boiler group based on the first control pressure band when the boiler pressure rises, and by shifting each pressure band of the first control pressure band downward, the header pressure A second control pressure zone storage unit for storing a second control pressure zone, wherein the combustion amount reduction timing of the boiler group when the value is increased is reduced by a predetermined pressure from each pressure zone of the first control pressure zone; A second control unit that controls the timing of the combustion amount decrease of the boiler group when the header pressure value increases based on the second control pressure band; and hunting or the header pressure value that may cause hunting. A hunting detector that detects fluctuating pseudo hunting, and hunting or pseudo hunting is detected by the hunting detector, and then the header pressure value decreases. A control switching unit that switches the control of the combustion amount reduction timing of the boiler group when the header pressure value increases from the first control unit to the control by the second control unit when the header pressure value increases. It relates to a boiler system provided.

  Further, the hunting detection unit is configured such that the header pressure value is between a control upper limit pressure value set in advance as a threshold value at which the control device stops all the boilers and an upper limit pressure value of the set pressure range. This includes detecting, as a pseudo-hunting state, a fluctuation that occurs when the number of times that exceeds a preset second control upper limit pressure value or becomes equal to or greater than the second control upper limit pressure value exceeds the first number during the first time period. It is preferable.

  The hunting detection unit may be configured such that the header pressure value falls below a second control lower limit pressure value set in advance so that an absolute value of a deviation from the lower limit pressure value of the set pressure range is equal to or less than a first threshold value. It is preferable that the number of times that the pressure is equal to or less than the second control lower limit pressure value includes detecting, as a pseudo hunting state, a fluctuation that occurs during the second time.

  In addition, the hunting detection unit is configured so that the number of times that the pressure drop width when the header pressure value drops exceeds a preset pressure drop width value or becomes equal to or greater than the pressure drop width value during the third time. In addition, it is preferable to include detecting a variation that occurs more than the third number of times as a pseudo hunting state.

  According to the present invention, in a boiler system including a control unit that controls a combustion state of a boiler group including a plurality of boilers so that the header pressure value falls within a preset pressure range, a predetermined header pressure is set. When a rapid drop that satisfies the conditions occurs, the header pressure is quickly converged within the set pressure range to prevent the hunting phenomenon, and when the hunting phenomenon occurs, the hunting phenomenon is quickly converged. The boiler system which can be provided can be provided.

  Further, according to the present invention, when the boiler supplying steam stops abnormally for some reason and a shortage of the combustion boiler occurs, a rapid load increase exceeding the assumption occurs, If there is a sudden drop in the header pressure due to a situation that is not in time, etc., or if there is a fluctuation in the header pressure that may cause hunting, the header pressure should be promptly within the set pressure range. Thus, it is possible to provide a boiler system that can prevent the hunting phenomenon in advance and can quickly converge the hunting phenomenon when the hunting phenomenon occurs.

It is a figure showing the outline of the boiler system concerning a 1st embodiment. It is a figure which shows the outline of the combustion position of the step value control boiler which concerns on 1st Embodiment. It is a figure which shows the 1st control pressure zone divided into the several pressure zone for judging the timing of the combustion amount reduction | decrease at the time of the header pressure value rise of the boiler group 2 in 1st Embodiment. It is a figure which shows the 2nd control pressure zone divided into the several pressure zone for judging the timing of the combustion amount reduction | decrease at the time of the header pressure value rise of the boiler group 2 in 1st Embodiment. It is a figure which shows the 3rd control pressure zone divided into the several pressure zone for judging the timing of the combustion amount reduction | decrease at the time of the header pressure value rise of the boiler group 2 in 1st Embodiment. It is a functional block diagram which shows the structure of the memory | storage part in 1st Embodiment. It is a functional block diagram which shows the structure of the control part in 1st Embodiment. It is the figure which showed an example of the flowchart which shows the flow of a process of the boiler system which concerns on 1st Embodiment. It is a functional block diagram which shows the structure of the control part in 2nd Embodiment. It is the figure which showed an example of the flowchart which shows the flow of a process of the boiler system which concerns on 2nd Embodiment.

[First Embodiment]
Hereinafter, preferred embodiments of the boiler system of the present invention will be described with reference to the drawings.
First, the overall configuration of the boiler system 1 according to the present embodiment will be described with reference to FIG.
As shown in FIG. 1, the boiler system 1 includes a boiler group 2 including a plurality (three) of stage value control boilers 20, and a steam header 6 that collects steam generated in the plurality of stage value control boilers 20. A steam pressure sensor 7 for measuring the pressure value inside the steam header 6 (hereinafter also referred to as “header pressure value”), and a unit control device 3 having a control unit 4 for controlling the combustion state of the boiler group 2. .
The boiler group 2 generates steam to be supplied to the steam use facility 18 as load equipment.

Each of the plurality of stage value control boilers 20 includes a boiler body 21 in which combustion is performed, and a local control unit 22 that controls the combustion position of the stage value control boiler 20.
The boiler body 21 includes a water pipe and a burner, and heats can water supplied from a water source (water supply tank) (not shown) in the water pipe to generate steam.

  The local control unit 22 changes the combustion position of the step value control boiler 20 according to the steam consumption. Specifically, the local control unit 22 controls the combustion position of the step value control boiler 20 based on the number control signal transmitted from the number control device 3 via the signal line 16. Further, the local control unit 22 transmits a signal used in the number control device 3 to the number control device 3 via the signal line 16. Examples of the signal used in the number control device 3 include the actual combustion position of the stage value control boiler 20 and other data.

  The steam header 6 is connected to a plurality of step value control boilers 20 constituting the boiler group 2 via a steam pipe 11. The downstream side of the steam header 6 is connected to the steam use facility 18 via the steam pipe 12.

  The steam header 6 collects and stores the steam generated in the boiler group 2. The steam header 6 adjusts the pressure difference and pressure fluctuation of the one or more stage value control boilers 20 to be combusted, and supplies steam whose steam pressure value is fixed to the steam using facility 18.

  The vapor pressure sensor 7 is electrically connected to the number control device 3 via the signal line 13. The vapor pressure sensor 7 measures the vapor pressure value of the vapor header 6 (hereinafter also referred to as “header pressure value”), and sends a vapor pressure signal corresponding to the vapor pressure value via the signal line 13 to the unit control device 3. Send to.

  The number control device 3 is electrically connected to a plurality of step value control boilers 20 via signal lines 16. The number control device 3 calculates the required steam amount of the boiler group 2 according to the required load based on the header pressure value measured by the steam pressure sensor 7, and the boiler group 2 based on the calculated required steam amount. Among these, the combustion position (combustion amount) of the stage value control boiler 20 (hereinafter also referred to as “control target boiler”) to be controlled is controlled.

Next, the several step value control boiler 20 which comprises the boiler system 1 is demonstrated. FIG. 2 is a diagram showing an outline of the boiler group 2 constituting the boiler system 1.
As shown in FIG. 2, the step value control boiler 20 of the present embodiment is
1) Combustion stop position (first combustion position: 0%),
2) Low combustion position L (second combustion position: 50%),
3) A step value control boiler (hereinafter also referred to as “three-position control boiler”) having a stepwise combustion position at a high combustion position H (third combustion position: 100% (maximum combustion amount)).
The maximum amount of steam that can be output by the step value control boiler 20 is referred to as the maximum output steam amount.

In the combustion control of the boiler system 1 described above, the pressure control zone is divided into a plurality of pressure zones. And the boiler system 1 sets the combustion state (combustion position) corresponding to every pressure zone, and determines the combustion state (combustion position) of each boiler 20 by which pressure zone corresponds to a header pressure value. Is done.
FIG. 3A is a diagram showing a relationship between the combustion state (combustion position) of each boiler 20 according to the present embodiment and a plurality of pressure zones in the pressure control zone.
In the present embodiment, as shown in FIG. 3A, the combustion state (combustion position) of the boiler 20 is “H” when the boiler is in a high combustion state in which the boiler is burned at the high combustion position, and low in the combustion state at the low combustion position. The case where the combustion state is set is indicated as “L”, and the case where the combustion stop state is set is indicated as “−”.

  As the combustion state (combustion position) of the boiler 20, a combustion state (combustion position) with a smaller combustion amount is selected as the header pressure value detected by the vapor pressure sensor 7 increases, and the combustion amount as the header pressure value decreases. A large combustion state (combustion position) is selected. As shown in FIG. 3A, in this embodiment, the pressure control zone is divided into seven pressure zones a to g. The boiler system 1 sets the combustion state (combustion position) of each corresponding boiler 20 for each pressure zone, and the combustion state (combustion) of each boiler 20 depends on which pressure zone the header pressure value corresponds to. Position). Seven combustion states (combustion positions) of each boiler 20 are set corresponding to the seven pressure bands.

  More specifically, as shown on the left side of FIG. 3A, in the highest pressure zone a (when the required load is small), all the boilers 20 are positioned at the combustion stop position (−), and the lowest pressure In the band g (when the required load is large), all the boilers 20 are located at the high combustion position (H).

The left side of FIG. 3A shows a control pressure band for determining an increase in the combustion amount when the pressure decreases (hereinafter also referred to as a “control pressure band when the pressure decreases”), and the right side shows a decrease in the combustion amount when the pressure increases. A control pressure band ("first control pressure band") is defined separately, and both are shifted by a differential amount.
That is, on the right side of FIG. 3A, when the header pressure value is in the increasing direction (load amount decreasing direction), the combustion state (combustion position) X having a large combustion amount shifts to the combustion state (combustion position) Y having a small combustion amount. When the header pressure value serving as a reference and the header pressure value on the left side of FIG. 3A are in the descending direction (load amount increasing direction), the combustion state (combustion position) Y from the low combustion amount (combustion position) A predetermined difference (differential) is provided between the header pressure value serving as a reference for shifting to (position) X so that the former (when rising) is larger than the latter (when descending).
If the differential is not provided, the combustion state (combustion position) may change frequently when the header pressure value fluctuates around the combustion amount increase / decrease line. Provided.
Note that the first control pressure zone is a control pressure zone that is normally used.

  A priority order is set for each of the boilers 20. The priority order is used to select a boiler that performs a combustion instruction or a combustion stop instruction. The priority order can be set, for example, using an integer value so that the lower the numerical value, the higher the priority order. As shown in FIG. 2, when the priorities of “1” to “3” are assigned to the first to third units of the boiler 20, the first unit has the highest priority and the third unit has the highest priority. The lowest. This priority order is changed at predetermined time intervals (for example, 24 hour intervals) under the control of the control unit 4 described later.

  In the present embodiment, as shown in the left side of FIG. 3A (control pressure zone at the time of pressure drop), when the vapor pressure decreases from the highest pressure zone a toward the lowest pressure zone g, After the higher priority boiler (here, No. 1 boiler) is changed from the combustion stop state (-) to the low combustion state (L), the next highest priority boiler (here, No. 2 boiler) -) Is changed to a low combustion state (L). After all the boilers 20 are changed to the low combustion state (L), the boiler 20 having the highest priority (here, No. 1 boiler) is changed from the low combustion state (L) to the high combustion state (H). The

  Conversely, as shown in the right side of FIG. 3A (first control pressure zone), when the vapor pressure rises from the lowest pressure zone g toward the highest pressure zone a, usually the lowest priority is given. After the boiler (No. 3 boiler) is changed from the high combustion state (H) to the low combustion state (L), the next highest boiler (No. 2 boiler) is changed from the high combustion state (H) to the low combustion state (H). The combustion state (L) is changed. After all the boilers 20 have been changed to the low combustion state (L), the boiler 20 having the lowest priority (here, No. 3 boiler) is changed from the low combustion state (L) to the combustion stopped state (-). The

Combustion of the stage value control boiler 20 or its stop can be handled in units of virtual boilers. With a virtual boiler, the difference in combustion position (combustion amount) (low combustion position, high combustion position) in the boiler is regarded as an independent boiler, and the steam amount at each combustion position and the steam amount at the combustion position one level lower than that This is a hypothetical difference in the amount of steam in the boiler.
For example, as shown in FIG. 2, the three-position control boiler can be composed of two virtual boilers, a low combustion amount boiler and a (high combustion amount−low combustion amount) boiler. For example, when a three-position control boiler is burned at a low combustion position, a combustion instruction is given to the low combustion amount boiler, while a combustion stop instruction is given to the (high combustion amount-low combustion amount) boiler. And can be handled for control.

  If it does so, the combustion priority which is the combustion order of the combustion position of the several step value control boiler 20 used as the control object of the boiler group 2 will change the stage value control boiler 20 used as a control object to a low combustion amount boiler, (high combustion amount). -Low combustion amount) When it is composed of two virtual boilers of boilers, the priority order when giving a combustion instruction and a combustion stop instruction for a plurality of virtual boilers constituting a plurality of stage value control boilers 20 to be controlled ( Hereinafter, it can be said to be equivalent to “virtual boiler priority”.

  Next, the configuration of the number control device 3 will be described in detail. As shown in FIG. 1, the number control device 3 includes a control unit 4 as a control unit and a storage unit 5.

The control unit 4 performs the combustion control by the proportional distribution control of the boiler group 2, but the pressure decrease divided into a plurality of pressure bands for determining the timing of the increase in the combustion amount of the boiler group 2 when the header pressure value decreases. A first control pressure zone, a second control pressure zone, and a third zone divided into a plurality of pressure zones for judging the timing of the combustion amount decrease of the boiler group 2 when the header pressure value rises Based on the control pressure band, the combustion state (combustion position) of each boiler 20 is controlled.
Details of the control unit 4 will be described later.
Note that the first control pressure band, the second control pressure band, and the third control pressure band are performed together with the description of the storage unit 5.

The configuration of the storage unit 5 is shown in FIG. As shown in FIG. 4, the storage unit 5 includes a first control pressure zone storage unit 51, a second control pressure zone storage unit 52, and a third control pressure zone storage unit 53.
The first control pressure zone storage unit 51, the second control pressure zone storage unit 52, and the third control pressure zone storage unit 53 each determine the timing of the combustion amount reduction of the boiler group 2 when the header pressure value increases. The first control pressure band, the second control pressure band, and the second control pressure band divided into a plurality of pressure bands are stored.

  As described above, the first control pressure zone is a control pressure zone that is normally used.

As shown in FIG. 3B, the second control pressure band shifts each pressure band of the first control pressure band downward, and determines the timing of the combustion amount decrease of the boiler group 2 when the header pressure value increases. This is a control pressure zone that is lower than each pressure zone by a predetermined pressure.
By doing so, the second control pressure band is configured such that the differential is eliminated. However, the second control pressure band may be determined so that the differential is reduced. The upper limit value of the second control pressure band is preferably equal to the upper limit value of the first control pressure band.

  As shown in FIG. 3C, the third control pressure band shifts each pressure band of the second control pressure band further downward, and performs second control on the timing of the combustion amount decrease of the boiler group 2 when the header pressure value increases. This is a control pressure zone that is lower than each pressure zone by a predetermined pressure. The upper limit value of the third control pressure band is preferably equal to the upper limit value of the first control pressure band.

As shown in FIG. 3C, the third control pressure band shifts each pressure band of the second control pressure band further downward to control the timing of the combustion amount decrease in the boiler group 2 when the header pressure value increases. The pressure is lowered by a predetermined pressure from each pressure zone.
By doing so, the third control pressure band is configured such that the differential is reversed from the control pressure band during the pressure drop.

  In addition, the storage unit 5 includes a first pressure value to be described later, contents of instructions given to each step value control boiler 20 under the control of the number control device 3 (control unit 4), and from each step value control boiler 20. The setting information of the received information such as the combustion position and the setting information related to the change of priority (rotation) are stored.

Next, the configuration of the control unit 4 will be described in detail.
In the first embodiment, the control unit 4 determines whether the combustion pressure decrease when the pressure rises when the header pressure value has fallen to satisfy a predetermined condition, and then the header pressure value has changed from the fall to the rise. Instead of the one control pressure band, the combustion amount is reduced at a timing earlier than normal based on the second control pressure band or the third control pressure band.

  In order to realize such control, as shown in FIG. 5, the control unit 4 includes a first control unit 41, a second control unit 42, a third control unit 43, a required steam amount calculation unit 44, A first detection unit 45, a second detection unit 46, and a control switching unit 47 are included.

<First control unit 41>
The 1st control part 41 controls the timing of the combustion amount decrease of the boiler group 2 at the time of a raise of a header pressure value based on the 1st control pressure zone. As described above, the first control pressure band is used in the conventional proportional distribution control, and is shifted from the control pressure band at the time of pressure drop by a differential amount.

That is, referring to FIG. 3A, when the header pressure value rises, all of Units 1 to 3 are located at the high combustion position (H) across the two pressure bands (f, g), and the maximum combustion state is reached. It will remain unchanged.
Then, when the header pressure value reaches the upper limit value of the pressure zone f (that is, the lower limit value of the pressure zone e), the combustion amount of the boiler group 2 is reduced by the No. 3 unit being positioned at the low combustion position (L) for the first time. .
As described above, the control by the first control unit 41 is the case where the boiler group 2 is in the maximum combustion state across the two pressure bands (f, g) even when the header pressure is changed from the decrease to the increase. It remains unchanged.

<Second control unit 42>
On the other hand, the 2nd control part 42 advances the timing of the combustion amount reduction | decrease of the boiler group 2 at the time of a raise of a header pressure value.
That is, referring to FIG. 3B, when the header pressure value increases, only the first to third units are located at the high combustion position (H) only in the pressure zone (g).
When the header pressure value reaches the upper limit value of the pressure band g (that is, the lower limit value of the pressure band f), the combustion amount of the boiler group 2 is reduced by positioning the No. 3 machine at the low combustion position (L).
Thereafter, the combustion amount is reduced at a timing earlier than the control by the first control unit 41 for each pressure zone.
As described above, in the control by the second control unit 42, when the header pressure is changed from the decrease to the increase, the boiler group 2 is in the maximum combustion state only in the pressure zone f.
Thereafter, the output steam amount can be reduced at a timing earlier than the control by the first control unit 41.

<Third control unit 43>
On the other hand, the third control unit 43 further accelerates the combustion amount reduction timing of the boiler group 2 than the combustion amount reduction timing of the second control unit 42.
That is, referring to FIG. 3C, the third control pressure zone is configured such that the differential is reversed from the control pressure zone at the time of pressure drop.
When the header pressure value rises, all units 1 to 3 are located at the high combustion position (H) only in the pressure zone (g1), and the header pressure value reaches the upper limit value of g1 (lower limit value of f1). Then, the No. 3 machine is located in the low combustion position (L), thereby reducing the combustion amount of the boiler group 2.
Thereafter, the combustion amount is decreased for each pressure zone.
Since the upper limit value of g1 (lower limit value of f1) is located within the range of the pressure band g, the combustion amount can be reduced earlier than the second control unit 42.
As described above, the control by the third control unit 43 is compared with the timing of the combustion amount decrease by the first control unit 41 and the timing of the combustion amount decrease by the second control unit 42 when the header pressure is changed from the decrease to the increase. When the pressure rises, the amount of combustion can be reduced at an earlier timing.

<Required steam amount calculation unit 44>
Necessary steam amount calculating unit 44, for each control period, based on the pressure deviation is the difference between the upper limit pressure value of the set pressure range header pressure value, a proportional distribution control system, to calculate the required amount of steam MV _n.
Specifically, the required steam amount calculation unit 44 sets the steam amount (maximum output steam amount) in the maximum combustion state (high combustion position) preset for each boiler 20 constituting the boiler group 2 for each control cycle. the total value is multiplied by the ratio obtained by dividing the pressure deviation of the header pressure value (the difference between the upper limit pressure value and the header pressure value of the set pressure range) in the control range, and calculates the required amount of steam MV _n.

  Next, types of states in which hunting may occur are described, and the first detection unit 45 and the second detection unit 46 that detect states in which hunting may occur will be described.

<First detection unit 45>
The first detection unit 45 has a possibility that hunting may occur, the header pressure value has fallen to satisfy a predetermined condition, and then the header pressure value has changed from falling to rising (hereinafter referred to as “first state”). ").
One factor that causes hunting is that when the steam load is low, an operation amount is excessively calculated more than necessary for a slight pressure change.
Specifically, at the time of low load, for example, when the header pressure value drops from standby for all units, a combustion instruction is issued to the boilers more than necessary, after which some boilers start combustion, and the header pressure Even after the value has started to rise, the amount of combustion is increased too much, so the pressure fluctuations suddenly move up and down, and hunting is considered to occur.
In the first embodiment, a fluctuation state (first state) is detected in which a decrease that satisfies a predetermined condition occurs in the header pressure value, which may cause hunting, and then the header pressure value changes from a decrease to an increase. By doing so, it is possible to reduce the amount of combustion in the boiler group 2 and to prevent the header pressure value from exceeding the control upper limit pressure value and stopping all cans and causing hunting.
Next, the type of the first state will be described.

[Type of first state (1)]
The header pressure value drops due to the header pressure value overshooting (for example, equal to or higher than the upper limit pressure value of the set pressure range), or the header pressure value falls and undershoots (for example, Thus, a state in which the header pressure value decreases due to being lower than the lower limit pressure value of the set pressure range occurs, and then the fluctuation state in which the header pressure value changes from decreasing to increasing is regarded as a kind of the first state.
In this case, it is considered that hunting may occur if the combustion amount is excessively increased even after the header pressure value has changed from a decrease to an increase.
The first detection unit 45 determines whether the header pressure value decreases due to the header pressure value overshooting, or the header pressure value decreases due to the header pressure value decreasing and undershooting. It is configured to detect a fluctuation state (first state) in which a drop that satisfies the condition has occurred and then the header pressure value changes from a drop to an increase.

[Type 1 of the first state (2)]
The header pressure value falls due to the header pressure value exceeding the control upper limit pressure value, or the header pressure value falls below the limit lower limit pressure value (the lower limit pressure not reached in normal control) A variation state in which a state in which the header pressure value decreases and then the header pressure value changes from a decrease to an increase can be regarded as a kind of the first state.
Also in this case, it is considered that hunting may occur if the combustion amount is excessively increased even after the header pressure value has changed from falling to rising.
The first detection unit 45 is configured such that the header pressure value drops due to the header pressure value exceeding the control upper limit pressure value, or the header pressure value falls below the lower limit limit pressure value (the lower limit pressure that cannot be reached under normal control). It is configured to detect a fluctuation state (first state) in which the header pressure value drops due to the occurrence of a drop that satisfies a predetermined condition in the header pressure value and then the header pressure value changes from falling to rising. The

[Type of first state (3)]
When the header pressure value exceeds the control upper limit pressure value, a state occurs in which the header pressure value decreases due to all the boilers 20 being in a standby state, and then the header pressure value changes from decreasing to increasing. The variation state can be regarded as a kind of the first state.
Also in this case, it is considered that hunting may occur if the combustion amount is excessively increased even after the header pressure value has changed from falling to rising.
When the header pressure value exceeds the control upper limit pressure value, the first detection unit 45 sets a predetermined condition for the header pressure value to decrease the header pressure value caused by setting all the boilers 20 to standby. It is configured so as to detect a fluctuation state (first state) in which a drop that satisfies the condition has occurred and then the header pressure value changes from a drop to an increase.

[Type 1 of the first state (4)]
The header pressure value decreases in a state in which the total value of the maximum output steam amounts of all the boilers 20 supplying steam is lower than the current required steam amount MV _n calculated by the required steam amount calculating unit 44, A hunting phenomenon may occur when the header pressure value falls below a predetermined pressure.

The total value of the maximum output steam of all the boiler feed蒸中is, the state below the required amount of steam MV _n at the present time calculated by necessary steam amount calculating unit 44 will be described some specific examples.

[When the steaming boiler stops combustion due to external factors]
For example, 7000 kg maximum output steam of the boiler 20 / h (i.e., boiler 20 7t boiler), the necessary amount of steam MV _n at the present time calculated by and necessary steam amount calculating unit 44 assumed 8t / h.

For example, when there are two boilers 20 being steamed and one of them is abnormally stopped, the total value of the maximum output steam amounts of all boilers being steamed is 7 t / h × 1 = 7 t / h. . On the other hand, since the current required steam amount MV _{n is set} to 8 t / h, the total value 7 t / h of the maximum output steam amount of all the boilers during steaming is calculated by the required steam amount calculation unit 44. Less than the required steam volume MV _n (8 t / h). In this case, the total value (7 t / h) of the maximum output steam amount of all the boilers during steaming is below the current required steam amount MV _n (8 t / h) calculated by the required steam amount calculation unit 44. It corresponds to.
Thus, when one of the steaming boilers 20 is abnormally stopped, the total value of the maximum output steam amounts of all the steaming boilers is calculated by the required steam amount calculation unit 44 at the present time. There is a possibility that a state below the required steam amount MV _n occurs. Then, if the header pressure value decreases, a hunting phenomenon may occur if the header pressure value falls below a predetermined pressure.

[In case of a sudden load increase that exceeds the expected level and the steam supply is not in time]
For example, a boiler 20 for feeding蒸中the two, the required load is increased abruptly, necessary steam amount MV _n is, for example, when it becomes 15 t / h, the maximum output steam of all the boiler feed蒸中The total amount is 7 t / h × 2 = 14 t / h. The total value 14 t / h of the maximum output steam amount of all the boilers during steaming corresponds to a state below the current required steam amount MV _n (15 t / h) calculated by the required steam amount calculation unit 44.
In this way, when a sudden load increase exceeding the assumption occurs, the current required steam amount calculated by the required steam amount calculation unit 44 is the sum of the maximum output steam amounts of all the boilers 20 during steaming. A state below MV _n may occur. Then, if the header pressure value decreases, a hunting phenomenon may occur if the header pressure value falls below a predetermined pressure.

Thus, the header pressure value in a state where the total value of the maximum output steam amounts of all the boilers 20 supplying steam is lower than the current required steam amount MV _n calculated by the required steam amount calculating unit 44. Is considered to be a kind of first state in which the header pressure value changes from falling to rising after that.
In this case, it is considered that hunting may occur if the combustion amount is excessively increased even after the header pressure value has changed from a decrease to an increase.
The first detection unit 45 is in a state where the total value of the maximum output steam amounts of all the boilers 20 supplying steam is lower than the current required steam amount MV _n calculated by the required steam amount calculating unit 44. A decrease in the header pressure value due to the header pressure value being lower than the predetermined pressure is regarded as a decrease in the header pressure value that satisfies the predetermined condition, and then the fluctuation state in which the header pressure value changes from the decrease to the increase (first) Configured to detect the condition).

As described above, the first detection unit 45 is configured to detect the first state described above.
Next, the second detection unit 46 will be described.

<Second detection unit 46>
When the first state is detected by the first detection unit 45, the second detection unit 46 further determines whether the gradient value with respect to the header pressure value decrease time is larger than a predetermined gradient value set in advance. Alternatively, it is detected that the decrease value of the header pressure value is smaller than a predetermined decrease value set in advance (hereinafter, the detected state is also referred to as “second state”).
It can be said that the second state is a case where there is a possibility of more intense hunting (standby for all units) than the first state detected by the first detection unit 45.

<Control switching unit 47>
When the first state is detected by the first detection unit 45, the control switching unit 47 controls the timing of the combustion amount decrease of the boiler group 2 when the header pressure value increases from the control by the first control unit 41 to the second. Switching to control by the control unit 42 is performed.
By doing so, as shown in FIG. 3B, when the header pressure value reaches the upper limit value of the pressure band g (that is, the lower limit value of the pressure band f), the No. 3 machine is positioned at the low combustion position (L). Control is performed such that the combustion amount of the boiler group 2 is reduced, and then the combustion amount is reduced for each pressure zone.
As described above, the output steam amount can be reduced at a timing earlier than the control by the first control unit 41 by the control by the second control unit 42.

Further, when the second state is detected by the second detection unit 46, the control switching unit 47 controls the timing of the combustion amount decrease of the boiler group 2 when the header pressure value increases to be controlled by the third control unit 43. Switch.
By doing so, as shown in FIG. 3C, when the header pressure value reaches the upper limit value (lower limit value of f1) of the pressure band g1, the No. 3 machine is positioned at the low combustion position (L), so that the boiler group 2 Then, the combustion amount is controlled to be decreased for each pressure zone.
Here, since the upper limit value of the pressure zone g1 is located within the range of the pressure zone g, the combustion amount can be reduced at an earlier timing than the control by the second control unit 42.
As described above, the output steam amount can be reduced by the control by the third control unit 43 at an earlier timing than the control by the first control unit 41 and the control by the second control unit 42.

As described above, when the first state is detected by the first detection unit 45, the control switching unit 47 switches the control by the first control unit 41 to the control by the second control unit 42, whereby the first control unit The output steam amount can be reduced at a timing earlier than the control by 41.
Similarly, when the second state is detected by the second detection unit 46, the control switching unit 47 switches the control by the first control unit 41 to the control by the third control unit 43, whereby the second control unit 42 The output steam amount can be reduced at an earlier timing than the control.
By doing so, the boiler system 1 suppresses the sudden vertical movement of the pressure fluctuation, quickly converges the header pressure value to a value within the set pressure range, prevents the hunting phenomenon, and the hunting phenomenon occurs. In this case, the hunting phenomenon can be quickly converged.

  Note that when the header pressure value converges to a value within the set pressure range while suppressing rapid vertical fluctuations in pressure fluctuation, the second control is performed when the header pressure value fluctuates around the combustion amount increase / decrease line. If the control by the unit 42 or the third control unit 43 is maintained, the combustion state (combustion position) may change frequently. Therefore, in such a case, it is preferable to restore the normal differential by the control switching unit 47.

That is, the control switching unit 47 switches the control of the combustion amount decrease timing of the boiler group 2 when the header pressure value increases to the control by the second control unit 42 or the third control unit 43, and then the header pressure value is set. In the case where the pressure starts to decrease without reaching the upper limit pressure value of the pressure range, the control of the timing of reducing the combustion amount of the boiler group 2 when the header pressure value increases is switched to the control by the first control unit 41.
By doing this, when the header pressure value converges to a value within the set pressure range, the combustion state (combustion position) does not change frequently when the header pressure value fluctuates around the combustion amount increase / decrease line. can do.
The function of the control unit 4 according to the boiler system 1 of the first embodiment has been described above.

  Next, operation | movement of the boiler system 1 of 1st Embodiment is demonstrated with reference to FIG. FIG. 6 is a flowchart showing a control flow of the boiler system 1.

In step ST1, the control unit 4 performs initial setting such as resetting of the first detection flag data and the second detection flag data. In addition, the control unit 4 initializes the first control unit 41 to control the timing of the combustion amount decrease of the boiler group 2 when the header pressure value increases.
The first detection flag data and the second detection flag data use a register, a bit memory, or the like as appropriate. When the first detection unit 45 determines the first state, and when the second detection unit 46 is in the second state, respectively. Is set when it is determined.

  In step ST2, the control unit 4 controls the combustion state of the boiler group 2 so that the header pressure value falls within the set pressure range for each control cycle.

  In step ST3, it is determined whether or not the first detection flag data or the second detection flag is set. If the first detection flag data or the second detection flag is set (Yes), the process proceeds to step ST10. Move. On the other hand, when the first detection flag data and the second detection flag are not set (No), the process proceeds to step ST4.

  In step ST4, the first detection unit 45 determines whether or not the first state is detected. If the first state is detected (in the case of Yes), the process proceeds to step ST5. If not detected (in the case of No), the process returns to step ST2.

  In step ST5, the first detection unit 45 sets first detection flag data.

  In Step ST6, the second detection unit 46 determines whether or not the second state is detected. If the second state is detected (Yes), the process proceeds to Step ST8. When not detecting (in the case of No), it moves to step ST7.

  In step ST7, the control switching unit 47 switches the control of the combustion amount decrease timing of the boiler group 2 when the header pressure value increases from the control by the first control unit 41 to the control by the second control unit 42. Thereafter, the process returns to step ST2.

  In step ST8, the second detection unit 46 sets second detection flag data.

  In step ST <b> 9, the control switching unit 47 switches the control of the combustion amount decrease timing of the boiler group 2 to the control by the third control unit 43 when the header pressure value increases. Thereafter, the process returns to step ST2.

  In step ST10, the control unit 4 determines whether or not the header pressure value has started to decrease without reaching the upper limit pressure value of the set pressure range, and the header pressure value decreases without reaching the upper limit pressure value of the set pressure range. If the operation has shifted to (in the case of Yes), the process proceeds to step ST11. If not (No), the process returns to step ST2.

  In step ST11, the control unit 4 resets the second detection flag data and the second detection flag data.

  In step ST12, the control switching unit 47 switches the control of the combustion amount decrease timing of the boiler group 2 when the header pressure value increases to the control by the first control unit 41. Thereafter, the process returns to ST2.

As described above, the boiler system 1 that uses the proportional distribution control method according to the first embodiment, when the header pressure value has fallen to satisfy a predetermined condition, and then the header pressure value has changed from falling to rising, A process of switching the control of the combustion amount decrease timing of the boiler group 2 when the header pressure value increases from the first control unit 41 to the control by the second control unit 42 is executed.
Thereby, the boiler system 1 using the proportional distribution control method according to the first embodiment, after the time when the header pressure value is changed from the decrease to the increase, the output steam amount at a timing earlier than the control by the first control unit 41. The amount of steam output from the boiler system 1 can quickly follow fluctuations in steam consumption (required load). As a result, the boiler system 1 can suppress the rapid vertical movement of the pressure fluctuation, quickly converge the header pressure value to a value within the set pressure range, and avoid the occurrence of hunting. Can be improved.

  Even when the header pressure value suddenly drops due to overshooting of the header pressure value, the boiler system 1 according to the first embodiment has the same effect by performing the same operation as described above. can get.

  Even when the header pressure value drops and undershoots, the boiler system 1 according to the first embodiment can obtain the same effect by performing the same operation as described above.

  Also, the header pressure value exceeds a control upper limit pressure value that is a value equal to or higher than the upper limit pressure value of the set pressure range, or the header pressure value falls below a control lower limit pressure value that is a value equal to or lower than the lower limit pressure value of the set pressure range. Even in this case, the boiler system 1 according to the first embodiment can obtain the same effect by performing the same operation as described above.

  Further, when the header pressure value exceeds the control upper limit pressure value, the boiler system 1 according to the first embodiment is the same by performing the same operation as described above even when a plurality of boilers are put on standby. The effect is obtained.

In the boiler system 1 using the proportional distribution control method according to the first embodiment, for example, when the boiler being steamed stops burning due to an external factor, or a sudden load increase exceeding the assumption occurs, and the steam supply is in time. The header pressure value is preset in a state where the total value of the maximum output steam amounts of all the boilers 20 during steaming is lower than the current required steam amount MV _n calculated by the required steam amount calculating unit 44. Even when a state where the pressure is lower than the first pressure value occurs, when the header pressure value changes from a decrease to an increase, the timing of the combustion amount decrease of the boiler group 2 when the header pressure value increases is controlled by the first control. The process which switches to the control by the 2nd control part 42 from the part 41 is performed.
Thus, the total value of the maximum output steam of all the boiler 20 the supply蒸中is in a state below the required amount of steam MV _n at the present time calculated by necessary steam amount calculating unit 44, the header pressure value is set in advance Even when a state below the first pressure value occurs, the boiler system 1 according to the first embodiment can obtain the same effect by performing the same operation as described above.

The boiler system 1 using the proportional distribution control method according to the first embodiment is a case where the header pressure value has fallen to satisfy a predetermined condition, and then the header pressure value has changed from the drop to the rise. Detects a second state in which the slope value with respect to the descent time is greater than a preset predetermined slope value, or the header pressure drop value is smaller than a preset predetermined fall value In this case, a process of switching the control of the combustion amount decrease timing of the boiler group 2 when the header pressure value is increased from the first control unit 41 to the control by the third control unit 43 is executed.
Thereby, the boiler system 1 using the proportional distribution control method according to the first embodiment is controlled by the third control unit 43 after the time when the header pressure value is changed from the decrease to the increase, so that the second control unit 42 is controlled. The amount of output steam can be quickly reduced at a timing earlier than the control by, and the output steam amount of the boiler system 1 can quickly follow the fluctuation of the steam consumption (required load). As a result, the boiler system 1 can suppress the rapid vertical movement of the pressure fluctuation, quickly converge the header pressure value to a value within the set pressure range, and avoid the occurrence of hunting. Can be improved.

The control switching unit 47 further switches the control of the combustion amount decrease timing of the boiler group 2 to the control by the second control unit 42 or the third control unit 43 when the header pressure value increases. After that, when the header pressure value does not reach the upper limit pressure value of the set pressure range and starts to decrease, the first control unit 41 controls the timing of the combustion amount decrease of the boiler group 2 when the header pressure value increases. A process of switching to control by is executed.
Thereby, when the header pressure value converges to a value within the set pressure range, if the header pressure value fluctuates around the combustion amount increase / decrease line, the combustion state (combustion position) is prevented from changing frequently. be able to.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. As will be described later, in the second embodiment, by detecting pseudo hunting, it is possible to prevent the header pressure value from exceeding the control upper limit pressure value and causing all cans to stop and hunting. .
The second embodiment will be described mainly with respect to differences from the first embodiment, and detailed description of the same configuration as the first embodiment will be omitted. In the second embodiment, the description of the first embodiment is appropriately applied to points that are not particularly described. Also in the second embodiment, the same effects as in the first embodiment are achieved.

<Configuration of control unit 4A>
A detailed configuration of the control unit 4A will be described. As shown in FIG. 7, the control unit 4A includes a first control unit 41A, a second control unit 42A, a hunting detection unit 43A, and a control switching unit 44A.

  The function of the first control unit 41A and the function of the second control unit 42A are the same as the function of the first control unit 41A and the function of the second control unit 42A in the first embodiment, respectively.

<Hunting detector 43A>
The hunting detection unit 43A detects pseudo hunting, which is hunting or a fluctuation in header pressure value that may cause hunting.
One factor that causes pseudo hunting is that, as in the first embodiment, when the steam load is low, the operation amount is excessively calculated more than necessary for a slight pressure change.
Specifically, at the time of low load, for example, when the header pressure value drops from standby for all units, a combustion instruction is issued to the boilers more than necessary, after which some boilers start combustion, and the header pressure Even after the value starts to rise, the amount of combustion is increased too much, so that the pressure fluctuation rapidly moves up and down, and it is considered that pseudo hunting (or hunting) occurs.
When the pseudo hunting phenomenon occurs, the header pressure value may exceed the control upper limit pressure value, and there is a possibility that all cans stop and hunting occurs.
In the second embodiment, by detecting such pseudo hunting, it is possible to prevent the header pressure value from exceeding the control upper limit pressure value and stop all cans and cause hunting.
Next, the type of pseudo hunting will be described.

[First pseudo hunting]
The header pressure value is preset as a second control upper limit pressure value between a control upper limit pressure value set in advance as a threshold value at which all the boilers 20 are stopped by the control unit 4A and the upper limit pressure value in the set pressure range. To do.
Control upper limit pressure value> Second control upper limit pressure value> Upper limit pressure value

In the second embodiment, the header pressure value does not exceed the control upper limit pressure value, but the fluctuation that becomes the second control upper limit pressure value or more is changed within the first time (for example, 60 seconds) within the first number of times (for example, 60 seconds). For example, a variation repeated four times or more is regarded as a kind of pseudo hunting (hereinafter also referred to as “first pseudo hunting”).
In addition, about 1st time and 1st frequency | count, it can set suitably according to the characteristic of the boiler system 1. FIG.
For example, when the first number of times is set to “1”, the hunting detection unit 43A has detected whether the header pressure value does not exceed the control upper limit pressure value, but has changed so as to become the second control upper limit pressure value or more. Detect whether or not.

[Second pseudo hunting]
Number of times the header pressure value falls below or falls below the second control lower limit pressure value set in advance so that the absolute value of the deviation from the lower limit pressure value of the set pressure range is less than or equal to the first threshold value However, the fluctuation occurring for the second number of times or more during the second time is regarded as a kind of pseudo hunting (hereinafter also referred to as “second pseudo hunting”).
In addition, about 2nd time and 2nd frequency | count, it can set suitably according to the characteristic of the boiler system 1. FIG.
In this case, when the second number of times is set to “1”, has the hunting detector 43A caused the header pressure value to fall below the second control zone lower limit value or below the second control zone lower limit value? Detect whether or not.

[Third pseudo hunting]
The number of times that the pressure drop width when the header pressure value drops exceeds the preset pressure drop width value or becomes equal to or greater than the pressure drop width value is the third time (for example, 60 seconds). A case where the header pressure value fluctuates rapidly above and below the target vapor pressure that occurs more than once (for example, four times) is regarded as a kind of pseudo hunting (hereinafter referred to as “third pseudo hunting”).
In addition, about 3rd time and 3rd frequency | count, it can set suitably according to the characteristic of the boiler system 1. FIG.
For example, when the third number of times is set to “1”, the hunting detection unit 43A causes the pressure drop width when the header pressure value PV drops to exceed a preset pressure drop width value or more than the pressure drop width value. (A third pseudo hunting state) occurs, and a fluctuation that occurs one or more times during the third time period is detected as a third pseudo hunting state.

<Control switching unit 44A>
When the hunting or pseudo hunting is detected by the hunting detection unit 43A and the header pressure value is changed from the decrease to the increase, the control switching unit 44A controls the timing of the combustion amount decrease of the boiler group 2 when the header pressure value increases. Is switched from the first control unit 41A to the control by the second control unit 42A.
By doing so, as shown in FIG. 3B, as in the first embodiment, for example, when the header pressure value reaches the upper limit value of the pressure band g (that is, the lower limit value of the pressure band f), By being located at (L), the combustion amount of the boiler group 2 is decreased, and thereafter, the combustion amount is controlled to be decreased at a timing earlier than the control by the first control unit 41 for each pressure zone.
As described above, the output steam amount can be reduced at a timing earlier than the control by the first control unit 41 by the control by the second control unit 42A.
As a result, the boiler system 1 can suppress the rapid vertical movement of the pressure fluctuation, quickly converge the header pressure value to a value within the set pressure range in the pseudo hunting stage, and avoid the occurrence of hunting.

  Also in the second embodiment, similarly to the first embodiment, the control switching unit 44A controls the timing of the combustion amount decrease of the boiler group 2 when the header pressure value is increased to the control by the second control unit 42A. After the switching, the first control unit controls the timing of the combustion amount decrease of the boiler group 2 when the header pressure value increases when the header pressure value starts to decrease without reaching the upper limit pressure value of the set pressure range. It is preferable to switch to the control by 41A.

  Next, operation | movement of the boiler system 1 of 2nd Embodiment is demonstrated with reference to FIG. FIG. 8 is a flowchart showing a control flow of the boiler system 1 according to the second embodiment.

In step ST21, the control unit 4 performs initial setting such as resetting the pseudo hunting flag data. In addition, the control unit 4 performs initial setting so that the first control unit 41 controls the timing of the combustion amount decrease of the boiler group 2 when the header pressure value increases.
The pseudo hunting flag data is set when a register, a bit memory, or the like is used as appropriate, and the hunting detection unit 43A determines hunting or pseudo hunting, respectively.

  In step ST22, the control unit 4 controls the combustion state of the boiler group 2 so that the header pressure value falls within the set pressure range for each control cycle.

  In step ST23, it is determined whether or not the pseudo hunting flag data is set. If the pseudo hunting flag data is set (Yes), the process proceeds to step ST27. On the other hand, if the pseudo hunting flag data is not set (No), the process proceeds to step ST24.

  In step ST24, the hunting detection unit 43A determines whether or not hunting or pseudo hunting is detected. If hunting or pseudo hunting is detected (in the case of Yes), the process proceeds to step ST25. When not detecting (in the case of No), it returns to step ST22.

  In step ST25, the hunting detection unit 43A sets pseudo hunting flag data.

  In Step ST26, the control switching unit 44A switches the control of the combustion amount decrease timing of the boiler group 2 to the control by the second control unit 42 when the header pressure value increases. Thereafter, the process returns to step ST22.

  In step ST27, the control unit 4 determines whether or not the header pressure value has started to decrease without reaching the upper limit pressure value of the set pressure range, and the header pressure value decreases without reaching the upper limit pressure value of the set pressure range. If the process has changed to (Yes), the process proceeds to step ST28. If not (No), the process returns to step ST22.

  In step ST28, the control unit 4 resets the pseudo hunting flag data.

  In step ST29, the control switching unit 44A switches the control of the combustion amount decrease timing of the boiler group 2 to the control by the first control unit 41 when the header pressure value increases. Thereafter, the process returns to ST22.

In the boiler system 1 using the proportional distribution control method according to the second embodiment described above, when the first pseudo hunting, the second pseudo hunting, or the third pseudo hunting is detected by the hunting detection unit 43A, When the header pressure value changes from a decrease to an increase, a process of switching the control of the combustion amount decrease timing of the boiler group when the header pressure value increases from the first control unit 41A to the control by the second control unit 42A. Execute.
Thereby, the boiler system 1 using the proportional distribution control method according to the second embodiment, after the time when the header pressure value has changed from the decrease to the increase, controls the output steam amount at a timing earlier than the control by the first control unit 41A. The amount of steam output from the boiler system 1 can quickly follow fluctuations in steam consumption (required load). As a result, the boiler system 1 can suppress the rapid vertical movement of the pressure fluctuation, quickly converge the header pressure value to a value within the set pressure range, and avoid the occurrence of hunting. Can be improved.

  The preferred embodiment of the boiler system 1 of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and can be modified as appropriate.

  In the present embodiment, the boiler group 2 includes the three step value control boilers 20, but is not limited thereto. The number of stage value control boilers 20 can be set as appropriate.

In the present embodiment, the three step value control boilers 20 are three-position control boilers, but the present invention is not limited to this. That is, the step value control boiler 20 of the present invention may be a four-position control or more boiler having a middle combustion position, or a two-position control step value control boiler, in addition to the three-position control.
Further, the boiler capacity of each stage value control boiler 20, the number of stages at the combustion position, the combustion rate at each combustion position, and the like may be different for each stage value control boiler 20.

DESCRIPTION OF SYMBOLS 1 Boiler system 2 Boiler group 20 Stage value control boiler 3 Number control apparatus 4 Control part 41 1st control part 42 2nd control part 43 3rd control part 44 Necessary steam amount calculation part 45 1st detection part 46 2nd detection part 47 Control switching section 5 Storage section 51 First control pressure band storage section 52 Second control pressure band storage section 53 Third control pressure band storage section 54 Priority order storage section 4A Control section 41A First control section 42A Second control section 43A Hunting Detection unit 44A Control switching unit

Claims (12)

A group of boilers composed of a plurality of stage value control boilers capable of burning at staged combustion positions;
A steam header for collecting steam generated in the boiler group;
Steam pressure measuring means for measuring a header pressure value which is a steam pressure value inside the steam header;
A preset maximum set pressure value as the upper limit of the set pressure range is defined is the set pressure range by a preset control range, the header pressure value measured by the steam pressure measuring means, the set pressure A control device for controlling the combustion state of the boiler group so as to fall within a range;
A boiler system comprising:
The controller is
A first control pressure band storage unit that stores a first control pressure band divided into a plurality of pressure bands for determining timing of combustion amount reduction of the boiler group when the header pressure value increases;
A first control unit that controls the timing of the combustion amount reduction of the boiler group when the header pressure value increases based on the first control pressure band;
The respective pressure zones of the first control pressure zone are shifted downward, and the combustion amount decrease timing of the boiler group when the header pressure value increases is lowered by a predetermined pressure from the pressure zones of the first control pressure zone. A second control pressure band storage unit for storing the second control pressure band;
A second control unit for controlling the timing of the combustion amount reduction of the boiler group when the header pressure value increases based on the second control pressure band;
A first detector that detects a first state in which a drop that satisfies a predetermined condition occurs in the header pressure value, and then the header pressure value changes from a drop to an increase;
When the first state is detected by the first detection unit, the timing of the combustion amount decrease of the boiler group when the header pressure value increases is controlled by the second control unit from the control by the first control unit. A control switching unit for switching to control;
A boiler system.   The boiler system according to claim 1, wherein an upper limit value of the second control pressure band is equal to an upper limit value of the first control pressure band.   The predetermined condition includes the header pressure value decreasing due to the header pressure value overshooting, or the header pressure value decreasing and undershooting. 2. The boiler system according to 2.   The predetermined condition is that the header pressure value exceeds a control upper limit pressure value that is equal to or higher than the upper limit pressure value of the set pressure range, or the header pressure value is a value equal to or lower than the lower limit pressure value of the set pressure range. The boiler system of any one of Claim 1 thru | or 3 including falling below the control lower limit pressure value which is.   The boiler system according to claim 4, wherein the predetermined condition includes placing all the boilers on standby when the header pressure value exceeds the control upper limit pressure value. The control device may further control every period, based on the pressure deviation the a difference between the header pressure value and the upper limit pressure value of the set pressure range, has the required steam amount calculating unit for calculating a required amount of steam MV _n ,
The predetermined condition is that the sum of the maximum output steam amounts of all boilers supplying steam is lower than the current required steam amount MV _n calculated by the required steam amount calculating unit, and the header pressure The boiler system according to any one of claims 1 to 3, comprising a value lower than a preset first pressure value. The control device further shifts each pressure band of the second control pressure band downward, and sets the timing of the combustion amount decrease of the boiler group when the header pressure value increases to each pressure band of the second control pressure band. A third control pressure band storage unit for storing the third control pressure band, which is further reduced by a predetermined pressure;
A third control unit for controlling the timing of the combustion amount reduction of the boiler group when the header pressure value increases based on the third control pressure band;
When the first state is detected by the first detection unit, the gradient value with respect to the descending time of the header pressure value is larger than a predetermined gradient value set in advance, or the header pressure value A second detection unit that detects a second state in which the decrease value of the second value is smaller than a predetermined decrease value set in advance,
When the second state is detected by the second detection unit, the control switching unit controls the timing of the combustion amount reduction of the boiler group when the header pressure value increases from the control by the first control unit. The boiler system according to claim 1, wherein the boiler system is switched to control by the third control unit. The control switching unit further includes:
After the control switching unit switches the control of the combustion amount decrease timing of the boiler group when the header pressure value increases to the control by the second control unit or the third control unit, the header pressure value is Switching to the control by the first control unit when the header pressure value increases and the combustion amount decrease timing of the boiler group when the header pressure value increases, when reaching the upper limit pressure value of the set pressure range. The boiler system according to claim 7. A group of boilers composed of a plurality of stage value control boilers capable of burning at staged combustion positions;
A steam header for collecting steam generated in the boiler group;
Steam pressure measuring means for measuring a header pressure value which is a steam pressure value inside the steam header;
A preset maximum set pressure value as the upper limit of the set pressure range is defined is the set pressure range by a preset control range, the header pressure value measured by the steam pressure measuring means, the set pressure A control device for controlling the combustion state of the boiler group so as to fall within a range;
A boiler system comprising:
The controller is
A first control pressure band storage unit that stores a first control pressure band divided into a plurality of pressure bands for determining the timing of the combustion amount decrease of the boiler group when the header pressure value increases;
A first control unit that controls the timing of the combustion amount reduction of the boiler group when the header pressure value increases based on the first control pressure band;
Each pressure zone of the first control pressure zone is shifted downward, and the timing of the combustion amount reduction of the boiler group when the header pressure value increases is lowered by a predetermined pressure from each pressure zone of the first control pressure zone. A second control pressure band storage unit for storing the second control pressure band;
A second control unit that controls the timing of the combustion amount reduction of the boiler group when the header pressure value increases based on the second control pressure band;
A hunting detector that detects hunting or pseudo-hunting that is a variation in the header pressure value that may cause hunting;
When the hunting detection unit detects the hunting or the pseudo hunting, and then the header pressure value is changed from the decrease to the increase, the control of the timing of reducing the combustion amount of the boiler group when the header pressure value is increased is performed. A control switching unit for switching from one control unit to control by the second control unit;
A boiler system.   In the hunting detection unit, the header pressure value is set in advance between a control upper limit pressure value that is preset as a threshold value at which the control device stops all of the boilers and an upper limit pressure value in the set pressure range. Detecting a fluctuation that occurs more than the first number of times during the first time as a pseudo hunting state, wherein the number of times that exceeds the second control upper limit pressure value or more than the second control upper limit pressure value. Item 10. The boiler system according to Item 9.   The hunting detection unit may be configured such that the header pressure value is lower than a second control lower limit pressure value set in advance so that an absolute value of a deviation from the lower limit pressure value of the set pressure range is equal to or less than a first threshold value. The boiler system according to claim 9 or 10, comprising detecting, as a pseudo hunting state, a fluctuation that occurs not less than the second number during the second time.   In the hunting detection unit, the number of times that the pressure drop width when the header pressure value drops exceeds a preset pressure drop width value or more than the pressure drop width value during the third time, The boiler system according to any one of claims 9 to 11, comprising detecting a fluctuation that occurs at least a third number of times as a pseudo hunting state.